For centuries around the globe cultural groups recognized and continue to recognize the existence of more than one gender. Conversations on gender have been framed on the notion that while multiple gender identities can and do exist, meeting the social needs of the cultural groups that define them, these gender identities are based on the existence of two distinct biological sexes. This makes sense when you consider how the biological sexes are defined: as male versus female. Males are defined by primary sexual characteristics, which include the presence of a penis, and secondary sexual characteristics, such as facial hair, an “Adam’s Apple”, and deep voices; females are defined by primary sexual characteristics, including the presence of breasts and a uterus, and secondary sexual characteristics, including higher voices and the ability to birth offspring. However, these are idealized characterizations, and not everyone meets these ideal types. Some men have high pitched voices and some women have facial hair. More recent medical evidence further demonstrates that this sex binary may be false. Today’s blog post will take a closer look at this evidence and explain how the sex binary is not actually the case but instead a spectrum.
In the 1990s scientists first began to realize that the dichotomy of two biological sexes may not be completely true. Genetic and medical studies began to shed light on this issue as published reports demonstrated two distinct cases: a woman pregnant with her third child went in for an amniocentesis and her doctor (as well as she) was shocked to discover that she carried XY DNA; an adult male who fathered four children went in for surgery and his doctor discovered he had a uterus, in addition to testes. Further study into these and other cases revealed that genetically sex was not simply XX for female and XY for male. It was discovered that an individual’s sex is actually based on 25 different genetic markers, which accounts for the variation we see in the sexes (e.g. different sized breasts and penises; men who can grow facial hair and me who cannot; women who can birth children and those who cannot).
Other studies demonstrated that greater comprehension of fetal development. It was discovered that in utero sex development begins during week 5 and continues on for several more weeks. During development a fetus could gain or lose various elements that would define it as a “him” or a “her”, retaining some of those characteristics genetically or morphologically. Oftentimes individuals do not realize this until later in life when a medical or genetic intervention occurs.
Physical anthropological studies also demonstrate issues with this sex binary. When it comes to identifying the sex of a deceased individual based on their skeletal remains there is a scoring system that ranges from 1 to 5. The ends of the range are the most diagnostic of either sex, whereas three is indeterminate. Scores of 2 and 4 are “likely” male or female. As someone who has assessed sex on multiple skeletons (over 100) it is clear that very few individuals consistently score 1s or 5s in all anatomical areas. When I explain the methods used for sexing to my students they will often seek out the morphological areas that they can touch (such as the back of the skull for the nuchal crest) and many panic because they do not meet the ideal of male or female (or even male or female at all). This demonstrates that these skeletal differences exist in life just as they do in death, and further call into question the notion of the sex binary.
Taken together the science is continuing to demonstrate that there is no sex binary. Instead sex exists on a spectrum. And that is okay. This spectrum has existed for centuries, just as multiple gender identities, and humans continue to exist, procreate, and do what they do. Therefore this information, although not new to nature but new to us, should not raise alarm. Instead, we should acknowledge it for what it is and realize that we should perhaps abandon archaic notions that no longer apply and accept those that do: sex is a spectrum.
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Ainsworth, C. (2015). Sex redefined. Nature.
Fausto-Sterling, A. (2018, October 25). Why Sex Is Not Binary . The New York Times.
Ford, A. (2015, February 24). Sex biology redefined: Article suggests that genes don’t indicate binary sexes. Retrieved from Scope: Standford Medcine: https://scopeblog.stanford.edu/2015/02/24/sex-biology-redefined-genes-dont-indicate-binary-sexes/
Kralick, A. (2018, December 25). How Human Bones Reveal the Fallacy of a Biological Sex Binary. Pacific Standard Magazine.
The Editors. (2017, September 1). The New Science of Sex and Gender. Retrieved from Scientific America: https://www.scientificamerican.com/article/the-new-science-of-sex-and-gender/